For years, researchers have known that large amounts of methane are frozen in permafrost soils, which may be released into the atmosphere as the climate warms.

But new research from NASA reveals that the Arctic Ocean itself may be a possible source of the potent greenhouse gas—and another potential contributor to global warming.

During five research flights, scientists detected concentrations of methane at higher altitudes than they had expected. Researchers believe that methane escaping from cracks in the sea ice contributed to higher-than-normal levels.

[Lead study author Eric Kort] noted that previous studies had detected high concentrations of methane in Arctic surface waters, but no one had predicted that this dissolved methane would find its way into the overlying atmosphere. Scientists are not yet sure how the methane is produced, but Kort suspects biological productivity in Arctic surface waters may be the culprit.

The photograph below shows cracks in the ice cover of the Arctic Ocean north of Alaska: